


Maybe the Ocean is Your Hand

by cheritsundere



Series: Say You'll See Me Again [2]
Category: Hunter X Hunter
Genre: Alternate Universe - Fantasy, Alternate Universe - Merpeople, Courting Rituals, Domestic Fluff, Family Bonding, Family Feels, Family Fluff, Fluff, Fluff and Humor, Flustered Killua, M/M, Nanika and Alluka are twins, Second-Hand Embarrassment, Trans Alluka Zoldyck, hand holding, rated t for mentions of the birds and the bees, shy Killua
Language: English
Status: Completed
Published: 2020-02-22
Updated: 2020-02-22
Packaged: 2021-02-28 05:41:55
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 13,532
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22845007
Author URL: https://archiveofourown.org/users/cheritsundere/pseuds/cheritsundere
Summary: “I’m not really sure what it is, but I found it yesterday when you went to Zushi’s pod to trade for some shrimp!” Gon explained excitedly. He left out the details of where exactly he found it since it was in the room Killua could never open. Firstly, he didn’t want to make him angry knowing that Gon had succeeded where Killua had failed. Secondly, it was more fun this way: Killua not knowing that he found it, making it a secret. “And well,” Gon scratched his cheek, “I want you to have it!”Killua almost dropped it.“You mean like -” he stuttered, face feeling hotter by the second. There’s no way Gon meant it like that. He was overthinking this way too much. He let out a quick giggle to quell his nerves and compose himself before continuing, “You mean as a cool find for us to add to our shelf collection, right? Not to me. Personally. Not like a -” Killua coughed, “I mean this isn’t a -”“It is. A gift, I mean.” Gon smiled, swishing his tail back antsy. “I hope you’ll accept it?---A Killugon Merfolk AU where Gon wants to court Killua, Killua wants to die, and Alluka and Nanika are surprised it took Gon so long in the first place.
Relationships: Gon Freecs & Alluka Zoldyck & Killua Zoldyck, Gon Freecs & Mito Freecs, Gon Freecs/Killua Zoldyck
Series: Say You'll See Me Again [2]
Series URL: https://archiveofourown.org/series/1632319
Comments: 43
Kudos: 300





	Maybe the Ocean is Your Hand

**Author's Note:**

> Hi there! First off, I would just like to say thank you to all the wonderful support I received on the first work of this series. Reading all the comments and seeing all the kudos in my inbox was an absolute joy and I'm so happy to see how much all of you readers liked reading it. I hope that this work is able to do the same for you as well.
> 
> This AU features Gon and Killua's life together with Alluka, Nanika, Mito, and Abe as a pod of merfolk, living in a system of cave tunnels by a coral reef off the shores of Whale Island. The rest of these notes will consist of a few Merfolk word definitions as well as information on the world this takes place in. While you can enjoy the fic without knowing these tidbits, I thought I would include them nonetheless for readers that want to know more about the rules of this world. In other words, feel free to skip the rest of these notes if lore isn't your thing, it won't ruin your reading experience in the slightest. Without further ado:
> 
> Tropical- A species of merfolk who live in warm waters, usually close to the equator. They are defined by their bright colors and family-centric mindset. Most Tropicals live in big tribes with populations reaching the hundreds and most pod members spanning generations. Tropics tend to be extremely territorial and sentimental, with pods living in the same system of tunnels for the entirety of their life. 
> 
> Nomadic - a species of merfolk who travel for a majority of their lives from place to place who tend to be loners. Occasionally Nomadics will settle down in one location once they find a mate though most decide to just travel together. 
> 
> Arctic - a species of merfolk who live in cold climates, often near the north or south poles. Characterized by their beautiful singing voices and light colored scales usually grey or white in color, Arctics tend to stay in smaller pods usually only consisting of immediate family members. They are adept hunters, able to usually take down big prey solo.
> 
> Whale Island Reef - a coral ecosystem home to a tribe of 37 merfolk pods. 87% of the population is Tropical, followed by 10% Nomadic, and lastly 3% are a different species. The ancestors of a majority of this tribe's members were close to humans and often did trade with them before some humans began hunting them. The tribe's leader, Bisky, still holds a pact with the humans who live on the island to ensure their safety, however contact with any humans if strictly off limits and knowledge of humans and their culture has been largely forgotten other than what has been preserved by way of mouth and fables told from one generation to the next.
> 
> Tribe - merfolk pods who inhabit a common domain and trade goods with one another as well as offer protection from predators.
> 
> Pod - a close-knit group of at least two merfolk who choose to live with one another in a dwelling. While most pod members are related to each other by blood or mating, it is not a requirement and some pods consist of completely unrelated members of even different species. Most mates leave to start their own pods once they are bonded.
> 
> Bonding - a ceremony through which two mates announce their commitment to one another by exchanging necklaces after courting one another for at least a month, if not longer. A bonded mer will never take on another mate in their lifetime, even if their mate shall die. 
> 
> Courtship - when at least two mer exchange gifts and signal their interest in one another as a mate. Most courtships go on for years before the pair decide to become bonded.

> Maybe I'm still the mermaid. Maybe the ocean is your hand. 

* * *

One bubble.

Killua takes a look around. Coast looks clear. Good.

Two bubbles.

Gon squirms to get a look, peeking around the coral. Ignoring Killua’s glare, he swims swiftly to the next rock formation, using the dark and dense seaweed fields for cover. He turns back around to blow bubbles at his friend, taunting and daring the blue-tailed merboy to try follow him before he leaves him behind, only to find that his advantage had been lost and Killua was already beside him, a smirk on his lips. The ruins are so close now, so close Gon can taste it. He gives Killua a quick tap on his right shoulder, hoping to distract him if only for a second, before zooming on ahead. 

He was going to win this time. He was-!

“Aha! I win!” Gon exclaimed, raising two fists into the air in celebration.

“Shut up-” Killua hissed at him, now all caught up, before lifting his right index finger to his lips and then whispering, “You dummy! You’re gonna attract attention! You know if even one shark shows up we’d be screwed!”

“But, Killua~,” Gon sang sweetly, “we checked! We’re safe! And we’re here now so-”

Killua flicked the merboy’s forehead before swimming further into the ship’s cabin, expecting Gon to, of course, follow right behind him after he finished whining about how he ‘always flicked him too hard’. He was such a guppy about that, yet never failed to act completely fine the next second. He saw Gon swim to float alongside him, sporting a pout and a pointed look. _What a drama queenfish._ He ignored his friend’s attempted guilt trip by swimming over to one of the sides of the room, seeing as there was probably another room on the other side of this blocked entrance as with many of the other ships they explored, and gave it a shove. _Ugh great._

This had to be at least the twentieth closed ‘door’ - as Killua called them - that they had found since they started their hunting trips last year. They were finally old enough to go off hunting on their own, without Aunt Mito’s - unnecessary in Killua’s opinion - watchful eye and Gon and Killua took the opportunity and swam with it. Every day when they were supposed to go off and get catch for their pod of six - Gon’s Aunt Mito, His Great-Grandmother Abe, Gon, himself, and his little twin sisters Alluka and Nanika - they decided to also go exploring. After all, it’s not as if Aunt Mito said they couldn’t do other things besides just hunting. Sure, it was technically ‘forbidden’ to try and seek out anything from the human world, and technically shipwrecks were one of such things but-

Okay, they were _definitely_ breaking the rules and Aunt Mito’s heart doing this, but hey. What she didn’t know couldn’t hurt her, right? 

This was Killua’s logic. Gon, on the other hand, took a lot of persuading the first time, but after they found those shiny round rocks that showed their reflection in their first ship, he changed his tune. Pretty soon they were both racing to leave for their hunting trips every morning before Aunt Mito could even wish them a good morning, ready to see what treasures they could find that day.

It was a lot of fun, if you asked him: finding strange rocks that shined bright all different colors, usually clear though, in chests along with round stones all the same size and bright shiny yellow in color. Sometimes they would find necklaces of pearls even! They must have been important items to the humans that once owned them, considering they were hidden away, but Killua honestly didn’t really understand it. He asked Gon one time, after finding another batch of yellow stones, what he thought they might be used for, as sometimes Gon had a sixth sense about things. The boy had shook his head, also not really getting the human’s logic, but suggested that maybe it was their form of currency or was something they could trade with other humans for food if hunting was bad that week. ‘Maybe like how Aunt Mito saves away our stash of clams?’ he remembered Gon suggest one time. He made a decent point, clams were a delicacy for most pods, only to be enjoyed on special occasions like bonding ceremonies or a hatching celebration, and they were always kept in the furthest back room of their cave tunnels. If a member of a pod ever got sick and hunting wasn’t so easy, a pod could trade some clams with another pod for a whole mess of fish or any healing seaweed salve they might have on hand. It was always important to have at least a few clams stored on hand. Maybe the yellow stones were hard to come by in the human world as well? It still seemed strange that they’d value anything that couldn’t be eaten though. Unless humans could eat stones. Now _that’d_ be something.

It was a lot of fun. But what _wasn’t_ fun? Doors. Doors were not fun in the slightest.

Killua huffed and tried pulling at the bottom of the door, hoping that maybe he could break it enough to squeeze through to the other side. Gon, meanwhile, busied himself looking through the ‘desks’, - another word Killua had made up for one of the many human objects they found exploring - searching for any treasures that might be hidden. Despite no such interesting finds other than a few sticks filled with ink and what looked to be white pieces of once dried seaweed with weird scribbles on them, Gon wasn’t deterred and went on to explore the rest of the room. He made his way through the bones of some of the dearly departed, wishing them happiness in the afterlife, before noticing a necklace hanging around the neck bones of one. Gently whispering his apologies to the owner, he lifted it off. 

While stealing in and of itself was bad, Gon knew that something like this, obviously cared for and worn close to a person’s heart, was too valuable to just be left at the bottom of the sea with no one to appreciate or remember it. He sent a small thought to the owner’s soul, wherever it may be, that he’d treasure it for them and take good care of it in their stead. Gon hoped that if - should he ever suffer the same sort of fate - someone saw the shells around his neck, and how important they were to him, they would keep and polish them, if not try and find his pod to return them to. While he could never hope to return this necklace to the owner’s family, he would do the next best thing and keep it safe for them. He smiled softly down at it.

“Hey, Killua, look at this!” he said, proud of his find, turning towards his friend who still seemed to be struggling with the door. He held up the necklace, the same color as all those yellow stones they always found. Hanging from it was what appeared to be another one of those stones, but it looked a little different and Gon noted that it also felt lighter. Seeing Killua’s eyes now focused and inspecting the treasure from a distance, he swam to give him a closer look. Killua took hold of it, turning the weird, lighter than normal, stone hanging from the necklace over, back and forth, rubbing it with his thumb to see if maybe it also felt different than normal. He was right, it was smoother than the others and -

Huh. What was _that?_

Killua looked at the edge of it. It almost look like -

“I think there’s something inside it,” Killua said, holding it closer and squinting at the side. Yep, there was a definite line there, just like how clams had when they were sealed shut. Maybe this was the human’s version of a clam? Wait, maybe these stones really could be eaten and but were just hard on the outside, just like normal clams?! Killua shook his head quickly. No, that was a stupid thought. If that were the case, all the other stones would have had the same type of closed openings like this one.

No, this one was definitely different.

“Really?! Open it, open it!” Gon swam around him excitedly, eyes sparkling. 

“ _Oi!_ Gon, calm down. I’m opening it, I’m opening it. _Jeez._ ” Killua scolded, hiding his own excitement at what might be inside. 

He dug his fingernails, now extended into his hunting claws, into the line, prying the stone open. With a little force, the stone opened to reveal what looked to be an amazingly detailed drawing of a woman, hair done into a bun and wearing a strange headpiece as well as adorned in some type of white stuff. Whoever drew this must have used amazing ink and put it onto rock that would never loose it’s stain. Even Killua’s cave drawings he had on the dry ceiling of his and Gon’s kelp-room would smear if either one of them splashed water on them, yet this drawing remained pristine and protected. This must have been one of the ‘photographs’ that Abe - Gon’s great grandmother - had talked about, sharing stories that were passed down from her own granddad, who was alive back when humans used to trade with the Merfolk so many years ago. According to Abe, photographs were something that humans made by using the light from the sun and glass lenses, to preserve an image onto dried white seaweed. 

Humans were amazing.

“Hmmmmm, that’s weird,” Gon hummed. “Human’s don’t have scales, right Killua?” Killua shook his head. “Then what is this? It can’t be a bunch of shells; it’d be way too hard to move. So is it that white seaweed stuff we find every now and then?” Gon continued, pointing at white stuff covering the woman’s chest. 

Gon was right. Merfolk often dressed themselves in dyed pieces of seaweed or shells as a sign of their bonds, both to their pods and their mate. Maybe humans did this as well? 

“Probably. Either that or humans have their own version of seaweed that they use and dye different colors too. I’m sure they have tons of different plants above water,” he offered.

“Well, whatever it is, it’s pretty!” Gon finally declared, taking another look at the picture. “I wish I had some of it to give to Aunt Mito to wear. It’d be perfect for ceremonies!”

Killua agreed. Judging by the photograph, he assumed that it was taken in honor of a special occasion. Abe did always say that photographs usually were used to commemorate events for history, such as a human’s election of a new tribe leader or bonding ceremonies. Maybe this was the woman’s coming of age photograph, when the human equivalent of growing in her adult tail fins happened. It’d make sense. Both he and Gon were given a shell headdress by Mito on their respective tail fin days, so it could be something similar for humans.

“Killua, we should ask Granny about it!” 

Bad idea.

“Are you stupid?” Killua squawked, “how’d that conversation go? ‘Hi, Abe! Killua and I were exploring one of those forbidden ships that Mito and you always warn us about going into and we found this necklace thingy inside. Can you tell us more about it? Don’t worry, we’ve only done this a few hundred times!’?” he said, sarcasm dripping in every word.

“We don’t have to do it like that,” Gon pouted. “We can just say that when we were hunting we saw something shining in the sand and thought it was a pretty shell but when we picked it up we noticed it looked like something from the human world!”

“And how would we explain how we know what something from the human world would look like, genius?” Killua asked.

“...Um. Because it...” Gon squirmed, “doesn’t look....like anything...else?” he finished, voice somewhat higher on the last word, hoping that it sounded believable as an excuse.

Killua sighed. 

* * *

“So you just found it?”

“Yes.”

“Lying there in the sand.”

“Uh-huh.”

“And you thought it was a shell and picked it up.”

“Yep.”

“But then you realized it wasn’t and you think the humans made it.”

“Yes.”

“Because it doesn’t look like anything else you’ve ever seen before.”

“Yep, that’s about it.”

The cave grew quiet. Alluka, Nanika, and Abe looked on from the seaweed mats on the floor, munching softly on fishcakes.

“I just have one last question for you two,” Mito said, arms crossed, stone-faced. 

Gon and Killua refused to make eye contact.

“Just how _dumb_ do you think I am?!”

* * *

After Mito’s long tirade about how ‘dangerous’ and ‘stupid’ and ‘so idiotic that she can’t believe they were born with more than two brain cells each’ going into a human’s shipwreck was, Abe told them all about the necklace and stones they had found that day. 

“This, is what the humans call a locket,” Abe started, holding the necklace delicately in her hands. Her eyes shone brightly, as if barely able to contain her wonder, countless untold stories hiding behind their irises. “It’s made from a type of metal, think of it like a type of rock, called gold. It’s a piece of jewelry that humans wear, very expensive, and - as you two discovered -” she continued, opening it, “the inside usually contains a photograph. Humans use the locket to keep photographs of their loved ones close to their hearts, safe and tucked away from prying eyes. Judging from this photo, I can assume this locket was owned by the woman in the photo’s spouse.” She smiled, noticing the merboys’ questioning looks, “the reason why I say this is she appears to be in a wedding dress.”

Wedding dress?

“What’s that?” Gon asked, blankly. Killua wasn’t going to lie: he hadn’t the slightest clue what a ‘wedding dress’ was either.

Abe chuckled.

“Well, you know bonding ceremonies and how - after courting for a least a full cycle of the moons - a couple will present each other with a bond necklace in front of their pod?” Abe asks. The boys nod together, silently ushering her to continue her explanation. “A wedding is the human equivalent of that ceremony. Once a couple has been courting another for a significant time, they exchange rings - a type of jewelry usually made from gold, worn on their fingers -” she explains in more depth, noticing their confusion at the word, “and vow to love one another forever in front of the human equivalent of their tribe or pod.”

Well. That was...informative, but-

“That still doesn’t really explain what a ‘wedding dress’ is,” Gon pointed out, wrinkling his brow.

“A ‘wedding dress’,” Abe laughed, mimicking the merboy’s tone of voice, “is adornment for the ceremony. It’s made out of cloth, a type of material made from flowers called cotton, that humans grow. Think of it like how we make seaweed shirts, only this type of adornment takes a lot of time to make and is worn only for such an occasion. A woman wears a wedding dress usually, while a man usually wears a suit. A suit is similar, but usually it’s black in color and has a bow around the neck,” she finished. 

“Huh, that’s kinda cool,” Killua grins, taking another look at the locket. “So, you think this is a photograph of her on the day of their wedding ceremony?”

“I’m quite confident,” Abe said. Killua seemed to marvel at the concept, now holding the locket and still staring at the photograph inside. She was surprised to see her great-grandson’s sad face at these words. Usually he was overjoyed at the mention of bond ceremonies, always talking about how great it was that two mer found each other and fell in love. So to see him like this was a strange sight to behold. 

“What’s the matter, angelfish?” she asked Gon, her tone obviously worried. At her question, Killua also looked at him, taking his eyes off the locket. 

“We didn’t find another locket there,” Gon said.

Killua raised an eyebrow. “Yeah? I mean, it’s probably-” 

He stopped, the thought finally catching up to him. Gon nodded, making a sad hum of agreement. Abe had also finally put the pieces together, a small murmur of realization escaping her lips. 

“She has it. She has the other locket. The owner was on the ship and it sank but she-” Gon started.

“-lived. Either she escaped before it went down or was never on the boat to begin with.” Killua finished.

The silence washed over them.

They were a bonded couple. They vowed to only love one another forever. They probably cared for no one else in the world more than each other.

And they died. Apart.

“She had to go on living without them,” Gon whispered, voice breaking a little. He was never good at this sort of stuff; always crying at any sad or bittersweet folk stories their tribe shared at get-togethers. “That’s the worst fate - knowing that the person you love the most is _never_ coming back and that you have to live without them.”

Abe remained quiet. It was a sad truth in life: everyone dies. No way around it. She knew her great grandson already knew this fact, but knowing and seeing it were two very different things. So young yet already so wise. He was right, it truly was, by far, probably the saddest thing-

“No, it’s not,” Killua stated, looking at Gon.

Abe’s eyes widened. _Ah._ Her great grandson may be wise, but it appears Killua was smarter still. 

“What are you talking about, Killua,” Gon demanded, hurt evident in his voice and on the verge of anger. “How could it be any worse?!”

“They could have both died together, knowing that neither of them could save the other,” he says. He smiles sadly at the thought. “She may have had to live on without them, but the owner died knowing that their love was still out there - safe and alive - up until their final moments. She could live on for the both of them. And I’m sure, when it was finally her time, she took her locket and her love to the grave as well. Knowing that they could finally be together again and that she had lived a lifetimes worth of memories in their honor.”

“ _Oh,_ ” Gon said, shakily.

Abe noticed the merboy’s tear-filled eyes, close to overflowing onto his cheeks, before wrapping him up in a warm hug.

“You’re right, Killua,” he cried into Abe’s shoulder, voice hiccuping. 

Gon tried not to think about it - how something like that would feel. It would be a crushing pain, like all the oxygen in his lungs would be sucked out. Like how he imagined humans would feel if they were drowning. Like he’d been buried under thousands of rocks.

Like how it would feel if he and Killua were about to die but there wasn’t a single thing he could do to stop it.

Later that night, Abe hangs the locket from Killua and Gon’s kelp-room ceiling, dangling like a dream catcher above Gon’s kelp bed. 

The locket stays on display there. They added a few other treasures to their collection overtime, placing some here and there on their shelves such as a ‘compass’, as Abe called it, that they found one day and a map of the human world that was made by charting the stars. Other shelves boasted ‘hats’ that some of the humans on the ship would wear or random jewelry that they had come across, mostly in chests or desks. However, only the locket remained there, high above the others, for Gon to see every night he went to sleep and every morning that he rose. Sometimes it’s there so that Gon can go to bed thinking with a prayer to the woman and her spouse, that he hopes they are happy together again in the afterlife. Sometimes it’s there so he can wonder about how strange and beautiful human customs and designs could be - fashioning a piece of jewelry out of yellow rock that contains a picture of your mate inside to keep with you at all times. 

Sometimes it’s there to remind him to never take the time he has with Killua for granted. 

* * *

“Can I open my eyes _now?_ ” Killua asks, tone incredulous. 

“Not yet!” Gon giggles, darting out of their secret base. Last year their room had begun to become too small to contain all their wonderful loot from their treasure hunts, according to Aunt Mito at least, so they set out find another hiding spot to store everything and had found ‘It’. ‘It’ was a series of tunnels, not too far away from their usual hunting grounds and about a five minute swim away from the shipwreck where they had found the locket - way back when. That was two years ago. Now...

Now Gon and Killua were 14. 

While both of them had long since grown in their tail fins back when they were 12 - the signal that both of them were finally growing up and were allowed to hunt on their own now - they were finally starting to become ‘young mermen’, as Aunt Mito lovingly called them. He noticed his voice begin to deepen and his scales grew to become an even brighter shade of green, as was normal and expected of him. He was so proud the day his first new scale came in, excitedly waking everyone up at daybreak and showing it off. ‘That’s cool, Gon’ he remembered Killua yawning, before asking Alluka to pass the shrimp and ignoring his obvious pout at being ignored. Nanika and Alluka were way more supportive, clapping in celebration and asking when he thought the next ones would be coming it. Turns out it wasn’t that long at all and he had almost a tail full of beautiful bright green scales by the end of the week. It was at that point that Killua finally had to congratulate him. 

_’They look...nice,’_ he mumbled, not meeting Gon’s eyes. Killua never gave out compliments. So, naturally, Gon was over the moon.

Killua’s changes were....

Different.

Gon noticed it almost immediately when it happened, probably before Killua noticed it himself. 

Weeks after Gon’s scales came in, he had asked Aunt Mito when Killua’s scales would start getting brighter, since Killua was only a few months younger than him. While he figured it wouldn’t be long, he still was excited to see what color they would be. After all, almost every merfolk in their tribe might have hatched with dull greens, browns, or blues, only to get brighter when they got older, but Killua had gray scales. Gon had never seen anyone with scales like Killua’s. 

‘ _Well, Gon, that’s because our tribe is mostly made of Tropicals, like you, me and Abe,”_ Aunt Mito explained, _‘Killua is. Well-’_ she struggled.

Different. 

Killua and his sisters were Arctics. 

Killua had explained as much when he first met him: their tribe was from the north pole but, the day Alluka and Nanika were able to swim strong and long enough, they left to start their own pod free of the rest of their family. While it wasn’t exactly normal, it wasn’t unheard of for Arctics to leave at such a young age, since most Arctic pods and tribes were small in size to begin with. Add that to all the horror stories Killua had shared about their mother and older brothers - exposing Killua to electric eels to ‘help him catch dangerous prey easier’ and telling Alluka and Nanika that they were merboys because of their birth, not allowing them to wear seaweed garments - it wasn’t a surprise to Gon to hear that they left. While living in warmer waters took a lot of conditioning and getting used to, according to what Killua and his sisters said, their pod would never look for them here, so close to the Equator. In a weird way, Gon was actually kind of thankful to their old pod, not for hurting his friends, of course, but for causing them to come across his tribe. 

If it wasn’t for them, he never would have met the siblings and invited them to join his pod.

Needless to say, Killua wouldn’t be growing in bright green or blue scales like Gon did.

Killua’s scales were much prettier in his opinion.

 _‘Killua!’_ Gon exclaimed one day when they were out hunting together, _‘you have a patch of silver!’_ He swam closer to his friend, poking at scales closer to the bottom of his tail. With the light trickling in from the morning’s sunbeams, they looked like they were practically glowing.

 _‘Oh great,’_ Killua soured, flicking his tail up so he could be at eye level with the offending scales, _‘it had to be freaking silver, huh? It couldn’t be a blue or any other of the millions of colors to choose from that could sorta blend in with the coral? Like my hair and eyes didn’t make me an eyesore to begin with, now I have to deal with a -’ he scowled, narrowing his eyes at the scales, ‘what do I even call it? A target sign for a tail? There’s no way I can hunt like this, the fish would see me immediately from a mile away! Ugh. Even after leaving my family is STILL screwing me over!’_

Gon couldn’t disagree more: he thought Killua was one of the prettiest merfolk he had ever seen before and his new scales only made him even more beautiful. He told Killua as much, but his friend only replied by turning a dark shade of scarlet and yelling at him to stop embarrassing him, before swimming ahead and challenging Gon to a race to the hunting grounds.

While Killua’s voice didn’t get deeper, it seemed to take on a more melodic sound and Gon often heard the merboy hum little tunes whenever it was his turn to prepare their meals for their pod and he was alone in the kitchen, or when he and Gon would be floating around in their treasure cave, fixing his hair with - what they assumed to be the human equivalent of a comb - an item Abe had called a ‘fork’. He asked Killua why he didn’t sing more often, or around the others, but he just shrugged saying that it just felt normal to sing like this. He assumed maybe his friend was just shy or insecure about his voice - although he couldn’t understand why since Killua’s voice was the most wonderful thing he had ever heard before - so that was why he only sung around Gon or by himself, but, whatever the reason, he was proud that Killua felt safe enough around him to share such songs with him. It was like they were his own private performances - performances that no one else in the whole entire ocean had the privilege of hearing - and he loved it. 

“Gon!” said voice yelled out impatiently, eyes still closed shut and waiting for Gon to hurry up and find whatever it was he was looking for. “If you take any longer I’m going to leave without you and Mito will scold you for being home late again!”

“I’m coming, I’m coming!” Gon laughed, not rising to Killua’s baseless warnings. He always threatened he’d go on home without him, but, come hell or high water, Killua would always be waiting for him no matter how long it took him. Even if it took Gon hours to finish up whatever he was working on, Killua never once left him behind. 

Aha! Gon plucked the beautiful blue pebble up from the pile of random other treasures before swimming out of the tunnel and holding it out for Killua to see. “Okay, you can open your eyes now!”

Killua mumbled a ‘finally’ under his breath before doing just that. He lifted an eyebrow at Gon’s smiling face before looking down at the blue pebble in his friend’s outstretched hands. “What’s this?” he asked, picking the pebble up with two fingers before holding it up to the light and peering through it. Inside the pebble, light danced and reflected the pattern of the waves above their heads, revealing a tiny kaleidoscope of colors. This had to be one of the most gorgeous rocks he had ever seen before. 

“I’m not really sure what it is, but I found it yesterday when you went to Zushi’s pod to trade for some shrimp!” Gon explained excitedly. He left out the details of where exactly he found it since it was in the room Killua could never open. Firstly, he didn’t want to make him angry knowing that Gon had succeeded where Killua had failed. Secondly, it was more fun this way: Killua not knowing that he found it, making it a secret. “And well,” Gon scratched his cheek, “I want you to have it!”

Killua almost dropped it.

“You what?” Killua choked out, voice cracking on the second word before clearing his throat. “You mean like -” he stuttered, face feeling hotter by the second. There’s no way Gon meant it like that. He was overthinking this way too much. He let out a quick giggle to quell his nerves and compose himself before continuing, “You mean as a cool find for us to add to our shelf collection, right? Not to me. Personally. Not like a -” Killua coughed, “I mean this isn’t a -”

“It is. A gift, I mean.” Gon smiled, swishing his tail back antsy. “I hope you’ll accept it?”

If Killua was red before he’d hate to see what color he was sporting now.

What was Gon thinking?! Aunt Mito and Abe both had drilled into them the proper way to initiate courtship at least a hundred times now. And what was one of the first steps? Gift giving.

“I-” Killua opened his mouth before clicking it shut once again. How the hell was he supposed to respond? Thank him?! Give him something in return?! Hit him upside the head for putting him in this situation?!!! 

Gon looked at him expectantly, still waiting for the merboy to collect his words. He wasn’t worried, per say, but every second Killua didn’t answer made him take back the pebble and play the whole thing off as a joke.

“Okay.”

Huh? What did Killua say?

“What?” Gon asked, swimming closer to hear him better.

“I said ‘okay’, okay?!” Killua shouted in Gon’s face before realizing his own words and turning red and quiet again, shrinking away and flicking his tail fin around embarrassingly. “Okay,” he mumbled, looking away from Gon, “I accept it.”

Gon squeezed him in a hug and only complained a little when Killua flicked his forehead after. 

* * *

The months seemed to fly by after Gon's first gift. While Killua was nervous at first about their relationship changing, he soon realized his fears were unfounded. Things were basically the same for the most part. Gon and he still went off exploring every day together, usually challenging each other to a race on the way to their destination. Whenever they got tired, they'd take a break and snack on their lunch that Mito had packed them before getting their second wind and flitting off to a new adventure. They'd still play fight and compete over who could bring home more fish - he was winning, by the way - as well as just hang out together lazily, either polishing up some of their finds from the ships or talking about who was the strongest mer in their tribe. All in all, everything was exactly the same.

Well. Not _completely_ the same.

Gon was, should he say, the doting type. Every day - whether they were hunting, exploring, swimming errands, or just relaxing at home - Gon would give him a present, without fail. Some were obviously more impressive than others such as the first gift he had ever received or this one really cool human toy Gon had found one day that was made of a pretty silver and hung from a string that Abe had referred to as a 'yo-yo'. Other gifts were less cool like the conch shell he gave him one day or that shark tooth Gon had found in a cavern, but Killua still appreciated them nonetheless. It was impressive enough that Gon was somehow able to find a new thing to give him everyday to begin with. While he loved the attention - and he did, really - it made him feel...

Okay, fine, it made him feel like a shitty mate in comparison. Here Gon was, finding the time and effort to find or make him presents every day since they started courting and he had given Gon exactly 3: a handwoven seaweed bracelet that took him a week to make, a human invention that magnified objects and let Gon be able to see the stars at night, and a matching courtship gem similar to the one Gon gave him, but red in color and slightly larger, so that they could wear them as a sign of their status as a couple. 

It's not like he wasn't trying or anything, it's just he wanted to make sure Gon really liked the gifts and that they showed how much Killua liked him. Gon was worthy of only the best gifts imaginable. Because of that though, it made it really hard to find stuff that he felt was good enough. Sure, gift giving was never supposed to be a competition - in fact it was quite common for gift giving to be fairly one sided in most relationships until moving onto the next step of courtship - but that didn't change the fact that Killua felt like he might be giving Gon mixed signals with his lack of reciprocation. 

Not only that, but there was also ' _That'_. 

'That' was what Killua called Gon's lack of personal space that only intensified since they started courting. He didn't think much of it at first and just figured Gon was unaware they were swimming closer than usual as of late or that their hands would brush against one another every now and again. About a week in and it was quite obvious that Gon was, in fact, _very_ aware about what he was doing. The brushes lasted longer and happened more frequently and he'd find Gon looking at him out of the corner of his eye at least twice a day before catching himself and looking away. It was when they were hunting one day that Gon locked their hands together for the first time. It was this incident that made him finally admit to himself the undeniable truth that Gon was flirting with him.

Killua had blushed the entire trip.

Gon was the doting type. The problem was himself. Gon was always the one to initiate the contact - holding his hand, pulling kelp out of his hair in the morning, even wrapping their tails together whenever they sat together - while he struggled to not die from embarrassment, let alone try and give affection back. The closest he got was when he wiped some ink off Gon's cheek after they ate squid one time and even _that_ left Killua a fumbling mess afterwards since Gon got all happy and hugged him as a thank you. 

No, Killua was barely able to keep up with Gon's efforts, although it wasn't for lack of trying. He just wasn't a real touchy-feely mer and he never had been. While he'd chalk it up to how he was raised, it didn't change the fact that he didn't feel confident being so forward towards Gon. He was fine with letting Gon lead and just following. Though, it made him worry.

Was Gon fine with that? He didn't want Gon to think he didn't like holding hands or that he found physical contact with his future mate disgusting. He _loved_ being this close with Gon and being the only mer he'd do these things with, he just couldn't say it without combusting. Was that pathetic of him? Not being able to even groom the merboy that might be his mate one day without turning into a blushing mess so he just avoided it? Was Gon regretting his decision of picking Killua to begin with? 

He really hoped that wasn't the case. 

* * *

“So seaweed, flounder, and what was the other thing?” Killua asked Mito, doing a mental check list. Alluka and Nanika hovered around behind him, closer to the cave’s exit and playing patty cake while waiting for their older brother. 

“Shrimp brine,” Mito reminded him, handing him big shell bowl filled with sea urchins and one of her homemade fish traps. “Tell Mr. Wing I said hello for me, please.”

“Will do,” he flashed her a smile before joining his sisters at the exit. “Oi, Gon! I’m heading out!”

“Okay! Be safe, guys!” Gon called from the kitchen, helping Abe prepare the fish. He really wanted to go with them to see Zushi but he couldn’t leave Aunt Mito and Abe with all the work. Not only that, but it had been a while since it was just the three of them. They loved having the siblings as part of their pod, wouldn’t have it any other way, but it was nice to just talk among themselves for once, like how it used to be.

Especially when he had a question he couldn’t ask with Killua around. 

“Hey, Aunt Mito? Can I ask you a question?” Gon began, descaling the tail of one of the tuna he had caught earlier today. She hummed for him to continue. “It’s kind of...awkward?” he squirmed.

“Gon, you know how proud I am that you told me about you and Killua exchanging gifts but I really think you should wait until after bonding before-” she started.

“No, nothing like that-” Gon whined, slightly embarrassed at his aunt’s insinuation. Killua and he hadn’t even kissed yet! Neither of them were in any rush whatsoever to go beyond the first three of the ten steps of courtship for a while. “And it’s not about me - well, not exactly at least.”

Mito raised her eyebrow, telling him to go on. 

“Well, I know that different species have different types of courtship customs beyond the universal gift giving step - and I know all our customs - but Killua...” he trailed off. How was he supposed to phrase his question?

“You want to make sure you don’t skip a few steps and make him uncomfortable since you don’t know what courtship is like for Arctics?” she smiled, chopping the kelp up into small bits before sprinkling it with sea urchin dust. 

“Exactly!” Gon nodded enthusiastically. “I mean, I know certain things are off limits, for sure, but I don’t know if something like grooming or hand holding is considered too soon either! I've been trying to do those things but Killua doesn't seem to want to. He doesn't reject more or anything, but I'm worried I'm making him nervous or that he thinks I'm going too fast. The last thing I want to do is upset Killua or make him think he isn’t worth taking the time to court him the right way.”

Abe, who was quiet up to this point, chuckled softly at her great grandson’s comment. “I assure you that you are in no danger of that, child. I’m sure you’ve been nothing but an absolute gentlefish to him.”

Gon puffed his cheeks out, blush lightly gracing his skin. Mito laughed at his antics. 

“What Abe means by that is that I’m sure Killua knows how much you like him and you’d never intentionally rush your courtship. If you ever came on too strong, I have no doubt that he’d let you know. Probably with a swift whack of a tail fin even,” she chuckled, playfully winking at him, referring to Killua’s tendency of physical retribution at any type of affection, from Gon or anyone else for that matter. The merboy was quick to embarrass while her nephew was anything but. 

“Yeah, but I guess I also want to know just in case. Well-” he huffed, removing the last scale on the fish,” What if Killua initiates one of their steps but I don’t know that’s what he’s doing? I don’t want to hurt his feelings and accidentally turn him down.” 

Mito stilled at that. She hadn’t even considered Killua being the one to attempt further progression of the courtship ritual. After all, her nephew always was a proactive little one, being the first one to call Killua and his sisters his friends and bring them into their pod as well as starting their courtship in the first place. Though she realized how unfair that was to Killua and his feelings upon further contemplation. Of course the merboy had his own pace and thoughts on their relationship. It only made sense that he may want to be the one taking charge for once and purposing that they go beyond the gift giving step. But, because Gon knew next to nothing about Arctic customs, it might go right over his head and leave Killua thinking he was rejected. 

Well, that wasn’t happening if Mito had anything to say on the subject.

“You make a wonderful point, Gon. You’re right; you definitely should learn about their courtship practices as well. It’s only considerate as his potential future mate,” she pat him on the head before sitting down on a seaweed mat and gestured for him to sit across from her so they could go over the step together. 

Gon brightened. 

“Grandmother, feel free to step in if I forget anything,” she said to Abe, who decided to join them on the mats as well. She nodded. “This may come as a shock, but you technically skipped a step as far as usual Arctic courtship goes,” she began, tone taking on a slightly more amused quality when she noticed Gon’s face turn worried. “Don’t worry, you couldn’t really do the first step before gift giving since it’s more of a, um, well -” she laughed, “more of an ‘Arctic only’ step as it’s basically second nature to them. Most don’t even realize they are doing it until the other joins in.”

“Joins in?” Gon asked. He flopped on his belly before propping up his head so it rested in the palm of his hands. It was better if he got in a more comfortable position to listen to Aunt Mito’s descriptions sooner rather than later. He had a feeling this might take a while.

“The first step in their courtship is usually serenading each other with a song,” she said.

A song? _Wait a second_ -  
  
“One mer will start singing as an invitation. If the other finds their voice pleasing and accepts, they’ll try and join in and harmonize. If their voices are compatible, the courtship officially begins and they begin searching for and trading gifts to prove their worth as mates,” she finished.

Gon’s eyes widened. 

“That’s what that was?!” Gon raised his voice with the question.

Aunt Mito cocked her head to the side at his words before asking, “What ‘what’ was?” 

Gon groaned before letting his head fall down to the floor, banging it softly in an attempt to punish his obliviousness. “Killua sings around me all the time! I thought he was just shy and didn’t like singing around everyone else, but now it makes _so_ much sense!” It wasn’t shyness at all! He was just singing to Gon because that was what Arctics did naturally around the mer they liked. 

Ugh. Killua was right: he _was_ stupid. 

Aunt Mito was quiet at the news for a second before bursting into laughter. Abe chuckled a little herself before patting her great grandson on the head gently. 

“I guess Killua really did make the first move then,” Aunt Mito said after catching her breath. 

Gon lifted his head, “I...didn’t think of it like that. But. That’s true. Killua courted me first technically...”

Abe decided to continue where they left off and reiterate that the second step was the usual gift giving of anything from shells to large catches in attempts to show off their potential at providing for their mate. Mito nodded her agreement before moving right along to the next few steps. 

“Step 3 through 5 tend are basically interchangeable, they don’t have to be in the order that I explain them, and could even be going on simultaneously, since Arctics consider these steps to be around the same level of intimacy in a courtship,” she started. Before continuing with her explanation, Mito took a deep breath and leveled her gaze, making sure she had direct eye contact with her nephew. “These are fairly important and not really ones that we Tropicals tend to label as courtship steps, since we tend to be more affectionate than other species. So I want you to pay attention to these, okay?” 

Gon nodded signaling that she had his full, undivided attention. 

“These steps can be summed up in basically three words, all starting with the letter ‘g’: Grooming, Gravitating, and Guarding,” Mito said, emphasizing each word by counting them off on her fingers. “Grooming is pretty self explanatory: a courting pair will often groom one another, whether this be after meals, before sleeping, or when they first wake up. While we groom others, even tribe members outside of our own pod - like Abe fixing Wing’s glasses and me cleaning Zushi’s mouth if he ever has fish crumbs - I’m sure you noticed Killua and his sisters tend to groom themselves, unless Alluka is having a bad hair day,” she says, voice taking on a fond and softer tone at the end. 

Gon giggled at that. Alluka would sometimes sleep restlessly and wake up the next morning with her hair in tangles and she’d be unable to fix it. It was during these occasions that she would approach Mito shyly and request the merwoman’s help. Of course, Mito had been thrilled the first time it had happened, knowing that the young mermaid was opening up to her. Gon noticed his aunt’s eyes crinkling at the memory before she decided to get back to her explanation and cleared her throat with a small cough. 

“Anyway, Arctics groom themselves, rarely even grooming other pod members, so grooming between two merfolk is seen as a fairly intimate act,” she finished before moving onto the next word. “Gravitating is slightly more, shall we say, nuanced.” Mito took second to choose her words carefully before continuing. “It’s when a couple becomes closer, choosing to spend more time together and more affectionate. It can be anything. Increasing the frequency of hunting, swimming leisurely together, hugging, holding hands, the list goes on and on; hence the idea of ‘gravitating’ towards one another.”

That seemed slightly more vague than the other steps and Gon mentioned as such. While Mito and Abe shared his sentiment, they assured him that it didn’t have to be taken as so cut and dry - it was vague for a reason and differed by couples. One gravitating pair may be extremely affectionate with one another, cuddling and even exchanging quick cheek pecks, while others would be more reserved and would only be seen sitting close together or holding hands on rare occasions. There was no official definition to explain this step, Mito explained. If and when Killua and Gon ever wanted to initiate this step, all he had to do was be sure Killua was comfortable with whatever display of affection Gon was giving and to always be mindful if he said he wanted space. Naturally, it was also implied that if Killua ever was being too affectionate - as if that could ever happen, Gon thought to himself - he was also allowed, encouraged even, to tell Killua that he wasn’t ready for that type of physical contact. After checking that Gon understood everything about Gravitating, Abe decided that she would elaborate on Guarding.

“Guarding is being protective of your mate. It’s making sure that they are safe during hunting trips and taking care of them during illness,” Abe said. “Now, I know you, angelfish,” she tutted at her great grandson, “and I know how possessive you can be of things you like, so this step doesn’t mean that you can go hovering around Killua all the time and get jealous of him doing things without you.” 

Gon rubbed the back of his head sheepishly. While he did tend to go overboard, hoarding treasures to himself and not always sharing his fish all the time back when he was little, he really did understand the differences when it came to mates. Killua wasn’t something to be had, he was his own mer. Sure, he didn’t want Killua to hang out all the time with Zushi over him or anything, but that was a lot different than saying he couldn’t. Even he knew that. 

“I think that’s just about it, angelfish,” Abe said, placing her hands in her lap. “Everything beyond these steps are the usual courtship rituals that I’m sure you don’t need a refresher on.” 

Gon quickly shook his head, blushing slightly. He really didn’t need another talk about kissing, having it been mentioned by Mito at least a dozen times after he got his tail fins. And he _definitely_ didn’t need a reminder about nesting or their first night together after being bonded. He only needed to learn that once and he’d never need to hear it again. 

It seemed only a few minutes later that they heard a voices echoing from their tunnel’s entrance, signaling Killua, Alluka, and Nanika’s return. 

"Back!" Killua stored away the shrimp brine in the back tunnel before bringing the rest of their trading haul from Wing and Zushi’s to Mito’s waiting arms, ready to be prepared and eaten for supper. While not immediately, Killua felt Gon’s eyes on him as he swam around ever since he had gotten back. Sure, it wasn’t as if he never held Gon’s attention, but usually that was when they were racing or if he was showing off how many spins he could do without getting dizzy - his personal best was 16 in a row. Gon unable to keep his eyes off him while he just, well, floated? That was new.

“What?” Killua asked, finally unable to ignore his glances. Did he have something on his face? In this hair? Wait, did his courtship braid fall out?! Killua reached his braid, feeling the blue pebble Gon had given him weeks ago still tied tightly at the end. _Phew_ , okay so at least it wasn’t that. Killua’s brow furrowed. What was it then?

“I’m just really happy you’re my mate,” Gon smiled at him, matter-of-factly, like that was the obvious answer. 

Killua flushed scarlet. How did he even say things like that with a straight face?!

“Wha- we aren’t even mates yet, you moron!” Killua hissed, as if that was the only problem with Gon’s comment. At that, Gon’s smile only grew wider.

“ _’Yet?’_ ”he asked, smile taking on an almost cocky look now.

Killua stilled. _Crap._ He walked right into that one, didn’t he? 

“You know what I mean!” he argued, swimming away before Gon could counter. Good luck trying to get the last word from a different room, Killua thought to himself. Gon seemed to have different plans.

“Uh-uh, Killua! No take backs!” he laughed, swimming to catch up with him. “You said ‘yet’! Meaning you definitely want us to be mates some day!” 

“Lalalalala-” Killua started yelling, trying to talk over him and end this conversation, “what was that, Gon, I can’t hear you~!”

“Ki-llu-aaaaa~” Gon whined playfully, wrapping his arms around his future mate’s waist. “No singing! You can’t just-”

“Nope.” Killua cut him off, “We’re not having this discussion so let go!”

From the other room, Mito, the twins, and Abe just smiled at one another, listening to the two bicker back and forth. It wouldn’t be long now until they’d be hearing bonding chimes in the currents, the mermaids joked to themselves, ignoring the merboys’ voices grow softer as they flitted from one end of the tunnels to the next before they swam eventually made their way outside, no doubt to go play while dinner was in its last stage of preparation.

* * *

“- are you even listening to me?” Killua asked dryly, his swimming now slowing down in tempo. 

“Yeah, of course?” Gon hummed alongside him, eyes still focused on their current fixation that lied between the two of them: the fingers currently woven tightly between his own.

“What’s the last thing I said?” Killua deadpanned.

“You asked me if I was listening to you,” Gon grinned at him. Killua, on the other hand, seemed less amused at Gon’s answer and flicked him with his tail before returning back to swimming again. “Okay, I’m sorry. I promise I’ll listen for real this time, Killua! Say it again. Please?” He gave the merboy’s hand a squeeze as if to try and apologize for his earlier lack of attention. It must have worked if Killua’s blushing face was anything to go by.

“I was saying that we should go look for a present to give Nanika today,” Killua said, squeezing Gon’s hand back. He was looking forward with a small pout to try and play off that he was still angry at Gon’s lack of attention, but it wasn’t working. Like always, the merboy always was able to see right through Killua’s act so he just swam closer and hummed in response. “I felt bad enough when Nanika got sad that Alluka’s fins came in before hers, so I think her gift should be something amazing so she knows how proud we are of her.”

“That’s a good idea! I wonder what she’d like though...” Gon nodded before brainstorming. 

It wasn’t as if Nanika was hard to please or anything but usually she would get a present that was matching or similar to her sisters, not only for convenience but also just because they loved being able to match one another. They had matching seaweed ribbons, earrings pink in color, and even had received identical hairbrushes when Killua and Gon found a matching set in a ship one day. For a tail fin ceremony, though, it was important that both Alluka and Nanika were given totally unique presents to represent their independence and new status as budding merwomen. Needless to say, even though they gave Alluka a pretty necklace they made from shells and rocks found on their travels for her ceremony, it’d be an insult to do the exact same thing for Nanika. Her gift would have to be just as intricate and filled with loved, but different for sure. Gon racked his brain trying to come up with a good idea, before he felt the telltale signs of steam rising off of his head. He sucked at this part of gift giving. Put him in a room filled with shells and seaweed and he could make you a thousand beautiful jewelry pieces, no problem. But having nothing to work with and using your imagination right away? That was a different story.

“Oi, dummy. I can hear your brain frying from over here. You look like a clownfish that got stuck in one of those vents by the coral for too long,” Killua laughed at him softly, blowing a bubble in his direction. “I didn’t ask you so that you could go and think yourself to death; I just wanted to get your opinion. I was thinking maybe we could fix that box thing we found and give it to her. Think it’s doable?”

The box thing? They still hadn’t even figured out exactly what it did yet and Killua wanted to give that as a tail fin present?

“Why _that_?” Gon asked curiously. 

“I was thinking about how much Nanika liked that jewelry box we found for Mito’s 30th hatchday. I’m sure the box is pretty similar to it, if not even prettier, so it might be something she would like. Also, I’m not gonna lie, it’s just really bothering me that we don’t know what it completely does yet,” he grunted, frustration gracing his features. Killua may not have been as stubborn as Gon was, but he didn’t like being unable to solve a challenging puzzle as much as the next merboy. So this box thing was driving him crazy. 

Gon smiled at him, silently agreeing. While he never would say it to his face - partly because he liked keeping a few things to himself and also because he didn’t want another flick to the forehead - this was the Killua he liked best. The thoughtful and devoted brother but also the driven and intelligent problem solver. Just looking at him, able to stay calm and focused on a task and always for someone else, never himself, amazed Gon. 

He always amazed Gon. 

“You’re doing it again,” Killua huffed. 

“Doing what?” Gon asked. To anyone else swimming by, he’d seem genuinely confused as to what Killua might be referring to. But to Killua’s ears and eyes, who knew every single expression he had ever shown, it was obvious that Gon knew immediately what Killua meant and was just playing coy. 

“You know exactly ‘what’,” he narrowed his eyes at Gon, not buying his innocent act. 

“Hmmm~, can’t help it,” Gon laughed, admitting to it right away. There was really no point in trying to fool him anyway. “It’s hard to look at you and not stare, Killua!”

_Flick._

“Yeah, okay, I deserved that one,” Gon grinned, rubbing his forehead. 

“Good to know you have some self awareness. Too bad it doesn’t stop you from saying it,” Killua mumbled, cheeks now completely red at Gon’s compliment. 

“Nothing wrong with just speaking the truth!” Gon laughed, placing a small kiss on Killua’s face before speeding off ahead. He knew he didn’t want to be close enough for another incoming forehead flick, so he swam on ahead to the ship to find the box instead. 

It was a shame that Gon refused to look behind him. If he’d just turn around and look, he’d see Killua sporting a lovely shade of pink and a smile full of adoration. 

* * *

“Hey, Big Brother? When you and Gon bond, are you going to go find you’re own cave tunnels to live in?” Alluka asked, currently braiding Nanika’s hair and weaving in the pink seaweed ribbon.

Killua choked. _Bonding?!_ That was _years_ into the future so why spring this question on him now?!!

“Nanika would like to know as well,” Nanika agreed, looking up from the opened box in her lap, it’s contents releasing a melody of twinkling notes. The figurine inside twirled about slowly to the song. A ‘music box’, Killua and Gon dubbed it, presenting it to Nanika months ago. Turns out Killua was right: Nanika had loved it, evident by her insistence on playing it anytime she could find a moment. 

“W-Well,” Killua started, cringing internally at how his voice cracked. How was he supposed to even start answering a question like this?! It’s not as if he was the only one deciding this sort of thing anyway. Obviously, he’d have to discuss it with Gon first! Of course, that type of answer wouldn’t do much to dissuade his little sisters’ sudden interest in the subject nor would it ever be a conversation he’d ever initiate with Gon in the near future. He’d die of embarrassment on the spot. Killua took a breath, before trying to approach the question in a different way. “Why do you guys want to know?” Killua asked them.

Alluka halted her braiding while Nanika softly closed her music box. The two grew quiet and refused to meet their brother’s worried look. 

“We’re sorry,” Nanika whispered, voice with a hint of sadness. “Nanika and Alluka are bad sisters.” 

Killua grew even more worried. Where was this coming from?

“We just-” Alluka continued where her sister left off. “We know that bonded pairs are supposed to do that: go off and start a new pod together. But we-”

Killua’s eyes widened.

“W-we-” she began crying, her hands failing to catch the tears before they made their way down her cheeks, “we don’t want you to go away, Big Brother! We don’t want you and Gon to leave! We know it’s selfish and we know it’s mean but we want to stay together forever! All of us! Auntie Mito, Granny, and-!” her voice cut off before another round of tears threatened to escape.

Okay, he was putting a stop to this right now.

“Whoa, whoa, whoa, whoa, _whoa_ ,” He started, “leaving you guys? Where the hell did you get _that_ idea?”

Nanika was the one to speak up this time. “Bonded pairs-”

“Bonded shmonded; when have Gon and I ever mentioned wanting to be like a normal ‘bonded pair’ and start raising guppies?” he hushed, swimming over to his sisters before pulling them into a hug. “Gon and I aren’t going _anywhere_. Even if we did want to move out for-” Killua blushed even thinking about it, “’privacy’, we’d never just leave you guys behind. A fisherman would have to catch and fillet us for either one of us to ever - _ever_ \- not see you guys every day. You will always be our pod, no matter what. Nothing, not even Gon and I getting bonded could change that. I promise. Okay?”

His sisters looked up to him, nodding, eyes filled with more water than usual, before burying their heads into each side of his neck and tightening their hold. Killua rocked back and forth, reminiscent of how he remembered he used to do for them when they were barely guppies, all the while humming a soft melody to soothe them. 

“Guys, I got the tuna from Kurapika-” Gon cut himself off, looking at the scene in front of him. 

In Nanika and Alluka’s room, curled up on a seaweed mat on the floor, lay three sleeping bodies, tears now dry and hearts filled with love. He grabbed a kelp blanket and gently laid it over their tails before wishing them sweet dreams and promising he’d wake them for supper, placing a kiss on Killua’s forehead before gently swimming to the kitchen to help Aunt Mito.

* * *

It was months later, rounding on their second anniversary before Gon noticed the change. Killua seemed slightly distant, coming up with excuses whenever he offered they go hunting or exploring a new ship they found. If Gon was slightly more insecure or more of a worried wart like Leorio, he’d think Killua was mad at him for something. It wasn’t like he was straight up avoiding him, but they usually were always together. For years now, Gon’s life consisting of waking up to a grumpy Killua, spending the day together exploring or running errands, and then racing home and eating before laying down to sleep at night to do the same thing tomorrow. He liked doing these things with Killua, there was nothing else he’d rather do, but now...

_‘Sorry Gon, gotta go do something.’ ‘Hm, maybe later, I’m busy today.’ ‘I can’t, I have something else planned today. Tomorrow though, for sure!’_

Something was up. He just didn’t know what it was.

“Hey, Alluka?” Gon asked one morning after Killua flitted off on his own, saying he’d get some supper while he was out and leaving him behind at home for the third time this week. “Did I say something to make Killua upset?” 

He watched Killua’s little sisters weave some dyed kelp into complicated twists, making a gift for Abe’s 70th hatch day coming up in two weeks. The twins had decided on making a large patchwork blanket made of five different colors of kelp and were close to being done with their project soon. They had been hiding it in Gon and Killua’s kelp room to not raise Abe’s suspicions, so it was often nowadays that Gon would find himself sitting and enjoying their company as they worked away, helping pick out a design for the pattern here and there or bringing them some snacks to munch on. It didn’t help that he was really lonely without Killua always around, so he’d take any distractions he could get. At Gon’s question, Alluka looked up from her craft and tilted her head. 

“No? I don’t think so? Why do you ask?” she said.

Gon hummed at that, before rolling over to lay on his back and look up at his ceiling. The locket they had found over four years ago hung over him, silently taunting him of his current situation. “He’s just felt really far away these last few weeks, you know?”

“You miss him,” Alluka stated more than asked. She knew how much Gon loved her older brother and vice versa. 

“I don’t mind him being busy or doing stuff without me every now and then, I just-” Gon groaned, flopping over with a slight pout, “I like it better when we do stuff together...” 

He was a needy mer. Aunt Mito and Abe had informed him of this on multiple occasions starting from the very first time Aunt Mito left to go hunting without him when he had to stay in bed with a fever. He flailed about the entire time she was gone getting next to no rest despite Abe’s best efforts at lull him to sleep. It wasn’t until Aunt Mito was sitting by his bedside, feeding him small bites of jellyfish for his illness, that he finally settled down and fell to sleep. It was just who he was, call it being selfish or needy or whatever you’d like: Gon liked having the people he loved within reaching distance and got antsy when they were gone. This was just the way he was.

And Killua was driving him crazy. 

“Why don’t you tell him?” Alluka asked.

“Because he _knows!_ ” Gon groaned again. “He knows how I get! Remember how he used to tease me about how clingy I was to Aunt Mito when I first met you guys? He knows I don’t do well with this sort of thing!”

Alluka and Nanika giggled at his outburst. Like their older brother, the twins had instantly took to Gon when they first met him. From the first time he saved Nanika from that shark, they knew Gon was a wonderful merperson and someone that they could trust. While he was the one that invited them into the pod, it was only through their insistence that Killua finally gave in and they became a little family unto their own. Gon had been like the missing puzzle piece to their brother and theirs’ lives they had never known wasn’t there in the first place and it was times like this that reminded them why: Gon was just such a likable person. Everything he did was amusing and interesting - even just watching him roll around like a lovesick fool. 

“And that’s why I asked if I said or did something. He’s doing this on purpose. He has to be,” Gon finished. 

“Killua has reasons,” Nanika smiled, still working on the blanket. “Not mad. Just reasons.” 

Alluka smiled at her sister before looking at Gon and nodding in agreement. “We’re sworn to secrecy, so we can’t say, but we promise Big Brother isn’t mad. It’s nothing bad, he just has to do it alone. Things will go back to normal soon; You’ll see.”

While he had his doubts, Gon trusted the sisters endlessly. He also knew that there were certain things that Killua and his sisters shared that were off limits to him. It wasn’t anything personal, it was just how things were. Everyone was entitled to keeping some secrets. 

It didn’t change the fact that Gon still really really missed him.

Another week and a half went by before Killua seemed to return to normal. He even was the one to ask Gon to go hunting together that day, sending a thrill right to Gon’s heart. Errands were swam together and exploration trips were a plenty again while Killua even seemed to be more affectionate that usual - being the first to grab Gon’s hand and even being the one to give Gon a peck on the cheek after supper one night. While he had to admit that those weeks without Killua had been torture, a little part of him found himself thinking it might have been worth it if this was how Killua was going to apologize. 

“I want to show you something,” Killua said one morning as he and Gon were getting ready to leave. He seemed slightly on the nervous side, Gon noted, but excited as well. He’d almost call Killua giddy if he didn’t know any better. 

“What is it?” Gon asked, grabbing his satchel. While they might not be going exploring today apparently, like Gon had originally planned, it was always good to be prepared. Who knows, maybe Gon would find some shells along the way to whatever Killua wanted to show him.

“What’s the point in telling you before I show you? That takes away all the fun.” He waited by the tunnel’s exit, doing a few small somersaults to kill time while Gon finished grabbing his things. “Trust me, it’s better to just wait until you see it yourself.”

“Okay then! I’m ready to go!” Gon cheered, excited for whatever surprise Killua had in store. 

With a grin, Killua offered Gon a hand and started leading the way. They past miles of coral and kelp, swam through a trench, and over at least five different chains of sea anemones before Gon began to realize they had ended up in almost a complete circle and were on their way back home. Did Killua get lost?

“Um-” Gon started, noticing that the tunnels home were soon coming into focus. If they kept swimming forward for another good 10 minutes, they’d definitely be back home. Maybe Killua took a wrong turn somewhere.

“Don’t worry,” Killua cut him off, slowing down slightly before guiding Gon downwards, into a small cavern. The entrance was wide enough for them to fit through, but obviously was still small enough to keep out predators. Gon wondered why they hadn’t ever found this place before, being so close to home to begin with, as it seemed to be safe enough if his first impressions were anything to go on despite the darkness inside. A little place like this would have been perfect as one of their treasure storage spots if it had a little more light to work with. “Wait here a sec.” Killua gave Gon’s hand a small squeeze before letting go and wading through the dark blanket of shadows. While he trusted Killua and knew he wasn’t that far away, a part of him still felt a shiver go down his spine as he strained to hear for any sign where Killua swam off to. Down in this place with so little light trickling in from above made it hard to tell up from down or left from right. Thankfully, at least the water was a nice and pleasant temperature, still warm enough to be comfortable and relaxing but cooler than most other caverns that Gon had visited in the past, so that helped relieve his nerves. 

A few moments later, Gon heard Killua hum a little somewhere to his left before light began to trickle into his vision. Huh, that was weird. Gon looked up again to confirm that, indeed, the only opening was above them so light really shouldn’t be coming in from any other place. While he wanted to wait patiently for Killua, he figured swimming a little bit closer to inspect this light wouldn’t be completely ignoring Killua’s wish for him to stay in one place. Just a little closer, not much. Killua wouldn’t mind that. 

“Huh.” Gon squinted at one of the little balls of light, now hovering between his palms. It’s faint glow pulsated slowly before it gradually became a brighter yellow and left Gon’s hands, floating over to a wall to his left. It then seemed to settle itself in a little groove in the wall, nestling comfortably into its little cubbyhole. Almost immediately the whole cavern began to light up with what Gon could only guess was over a hundred of the little lights now illuminating the walls of the cavern in a warm yellow glow and he finally got a view of the whole area. “Wow...” 

The place was huge. Beautiful shelves made out of what he recognized to be gold decorated the walls while framed photographs of what he assumed to be the human world lined them. What the humans called a ‘dinning table’ was placed in the middle of the room he was in while he could see that the floor of the cavern was covered in what the humans called ‘rugs’. Little knickknacks were placed here and there, while other inventions that Killua and he had made up names for adorned the floor space like pieces of furniture. He recognized every item in here. This was-

“What do you think?” Killua asked, smile slightly shy but genuine. 

“Did you do this?” Gon marveled, still taking it all in, swimming closer to each shelf in reverence and wonder. 

“Yeah, I found this place almost a month ago when you were at Leorio’s. You know, when Kurapika hurt his dorsal?” Killua explained, swimming over to float next to him. 

Kurapika had gotten himself injured trying to kill one of the Spiderfish members, a group of nomadic mer who often stole from other tribes, when they attacked the outskirts of their tribe’s territory by the edge of Whale Island’s reef. While everyone was thankful to Kurapika for defending their home and glad that the tribe was safe, many pods like Gon’s and Wing’s still were worried for their friend and fellow tribe member. For the whole week after his injury, Gon swam over to Leorio’s cavern to check up on him and bring them anything they might need. Leorio to begin with was a rather overprotective mate but seeing Kurapika in pain only made matters worse, leading Leorio to refuse to leave his side unless they were running low on food or medicine. After he got better, Gon constantly found himself on the side of thanks from both Leorio and Kurapika for being such a good friend to the both of them, despite him saying again and again that it wasn’t that big of a deal. 

It was just another one of Gon’s qualities that Killua loved about him.

“I wasn’t much help, but I figured the least I could do was not get in the way, you know? So I decided maybe I could explore and find something to cheer him up or something,” he continued, picking up one of the knickknacks from the shelf. He slipped the tiny string loop around his finger before letting the knickknack’s main silver portion fall down, watching as it hovered for a bit, turning, before returning back to Killua’s hand. This was probably his favorite of the treasures they had found since exploring and played with it often. “While I couldn’t find any ships we hadn’t been to before, I did find this place. It was a total letdown at first - completely empty and too dark to see more than my hand in front of my face, but then I noticed these little guys-” looking at one of the lights on the wall, “hanging around and they like it when you sing. We had some of them up north. They like the algae and stuff that grows in caverns with cooler waters and their bodies give off a glow when they’re around certain frequencies. Tons of pods would settle down in their caverns to use them as light sources, since, you know, you don’t get a lot of sunlight up there with all the snow storms and ice caps and we Arctics aren’t too bad at singing. No idea they even lived around here before last month,” he finished.

Gon adored them. He watched as they danced on the walls, flitting about as if they hadn’t a care in the ocean. He gave one a little nudge before it landed on his finger, fluttering its glowing wings, and then taking off again to float in a different direction. 

“Anyway,” Killua cleared his throat, trying to subtly get Gon’s attention, “I, uh, noticed the place had some potential when it was lit up like this so I started moving some of the rocks and making the tunnels and rooms a little bigger.” He swam over to the entrance of one of the four tunnels before gesturing Gon to follow him. “I was thinking this could be a kelp room?” Killua suggested, sitting down on a seaweed mat and pointing out all the space it had. This room had less decorations than the previous, but it was still obvious that Killua had put a fair amount of time into making it look cozy. “Or, whatever. I mean, we could also make it the kitchen.”

_Wait, ‘we’? And a ‘kitchen’?_

“Oh and,” Killua started again, grabbing Gon’s hand and leading him to another room before Gon could even open his mouth, “I thought this might be a good place to put the supplies and stuff since it’s more towards the back of the tunnels. What do you think?”

Gon, unable to find his voice, nodded fervently. 

“Yeah? Awesome, I wasn’t too sure at first but now I feel a lot better knowing you think so too,” Killua said. Was his voice...getting faster? It definitely had to be, Gon had never heard him talk like this before. “Oh and-” he lead Gon into another tunnel to the next room, “If the other room is a kelp room this could be the kitchen, or this could be the kitchen, I mean, which ever you want, I’m still not too sure about which one should be which but-”

“Killua?” Gon cut him off, noticing the merboy’s flushed face and, now, almost shaking voice. “Are you oka-”

“Do you like it?” Killua rushed out, tail flitting around nervously. “I mean..” he breathed in deeply, voice now returning to normal, and turned his gaze to the floor before whispering, “it still has a lot of work, but...”

But?

“I like it a _lot,_ Killua,” Gon assured him, grabbing both his hands and holding them gently. “But you seem really nervous so what’s wrong?”

Killua swallowed before lifting his gaze to meet Gon’s. Well, it was now or never.

“Do you want...to live here?” Killua asked. 

Gon’s eyes widened. “You mean like-”

“-Like _together._ ” Killua answered immediately before flushing and stuttering out, “A-after we’re bonded, I mean! I didn’t mean right now, because I just realized what that sounded like and-”

Gon cut him off with a huge squeeze, making tiny bubbles of air leave Killua’s lungs. 

“It’s perfect. I’d love to live here with you, Killua,” he laughed.

Killua sighed a breath of relief before hugging him back. “Thank god.”

“Is this what you’ve been doing by yourself the last few weeks?” Gon asked, pulling back to pout at him. “You didn’t have to make it a secret, you could have just asked me and I would have helped you! We could have decorated it together!”

“I know that, dummy. I just wanted to...” Killua squirmed a little as if trying to gather up the courage for his next words. “I hate this. This is embarrassing,” he muttered.

“Killua, just tell me!” Gon huffed.

“Fine, fine! I just wanted to...” Killua struggled, “make it nice. For us,” he finished, flustered and refusing to meet Gon’s eyes. 

It took about 5 seconds of silence for his words to sink in and make Gon start laughing.

“Wha- fine! Laugh at me! It was a dumb idea anyway-” Killua said, turning his back towards Gon and crossing his arms. Gon, in between catching his breath, grabbed his shoulders and spun him back to face him before wiping away a tear from the laughter and shaking his head fondly.

“I’m not laughing at you, Killua, I promise,” he said, his voice soft and smiling. “I just think it’s so funny.” 

“What is?” Killua asked, arms still crossed defiantly.

“I never thought you’d be the nesting type.”

A beat passed.

_Flick._

“Ow! Killua, what was that-”

“You know _exactly_ what that was for, Gon.”

Gon’s smile widened. He did. He knew.

* * *

“Hey Killua?” Gon said, exiting the cavern and reaching for his hand. Killua grabbed it before locking their fingers together.

“What?” he asked. 

“I’m really glad you’re my mate.”

* * *

> If you'd like to see some sketches I made of Gon and Killua for this au, click [here](https://drive.google.com/file/d/1OHEipQvwTiesZJCSrOtiRIsmJSLGttCo/view?usp=sharing)

**Author's Note:**

> Thank you again for reading and I hope you enjoyed yourself! If you liked what you read and want to leave a kudo or comment, I'd be overjoyed. Also, don't forget: If you have any suggestions for a future au you'd like to see me write, please leave them in the comments below. 
> 
> I hope you have a great day/night wherever you are and I look forward to seeing you guys soon.


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